Burden of Proof and Standards of Proof

1. Introduction

One of the most fundamental problems in resolving disputes in civil procedural law is determining who will prove which fact and to what extent the judge needs to be convinced. The parties may make completely contradictory claims about the same event; and the court may not always reach the absolute truth. This is where the burden of proof and standards of proof come into play.

In Turkish law, both Article 6 of the Turkish Civil Code and the Code of Civil Procedure No. 6100 regulate which party bears the burden of proof and by what criteria the judge will evaluate the evidence. The fundamental approach, also substantiated by Supreme Court precedents, is based on the "overriding probability" criterion in civil litigation. That is, if the occurrence of an event seems more likely, more plausible, and stronger than its non-occurrence, this is sufficient to convince the judge.

This article burden of proof , standards of proof, particularly the theoretical basis and practical application of the "prevailing probability" criterion ; the established approach of the Court of Cassation, its implications in different types of cases, and its strategic implications for lawyers will be discussed.

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2. The Concept of Proof in Civil Proceedings

2.1. The Purpose and Function of Proof

In civil procedural law, proof, in its most general sense, is the activity of enabling the judge to reach a conclusion about the existence or non-existence of a fact. Facts alleged by the parties do not produce legal consequences unless they are accepted as "having occurred" by the court. Therefore, proof is a necessary step for the realization of rights in substantive law.

Proof has two basic functions:

1. Convincing the Judge:
   The judge freely evaluates the evidence and forms an opinion as to whether the facts in dispute occurred.

2. Risk Sharing Through Burden of Proof Allocation:
   Burden of proof rules which party bears the legal risk . If a fact cannot be proven, the party bearing the burden of proof loses the case.

Therefore, proof is not merely a matter of presenting technical evidence; it is also a tool for risk distribution and legal security.

2.2. The Judge's Freedom to Evaluate Evidence

In the Turkish civil procedure system, of freely assessing evidence is generally adopted. Unless otherwise stipulated in the law, the judge:

• He/She freely chooses among the evidence ,

• No evidence is given precedence (for example, there is no hierarchy between witness testimony, written documents, and expert reports; the decision rests with the judge)

• Based on the credibility and consistency of the evidence, and its conformity to the ordinary course of life, an opinion according to his own perspective .

However, this freedom is not unlimited. The judge said:

• by the law "conclusive evidence" (for example, the requirement to prove something with a document in some cases).

• The reasoned judgment must explain which evidence it considers superior and why

• It cannot make arbitrary assessments; its assessments legal review .

In this context , "prevailing probability" emerges as an expression of the level of conviction a judge must reach when freely evaluating evidence

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3. Burden of Proof: Who Proves What, and When?

3.1. General Rule: Proofs Burdened by the Alleging Party (Turkish Civil Code Article 6 and Turkish Code of Civil Procedure Article 190)

Article 6 of the Turkish Civil Code establishes the general rule regarding the burden of proof:

Unless the law provides otherwise, each party bears the burden of proving the existence of the facts upon which it bases its claim.

The provision regarding the burden of proof in the Code of Civil Procedure also reiterates this general principle from the perspective of procedural law. Accordingly:

• A party making a claim (plaintiff, counterclaimant, defendant raising a defense),

• He/ she is obliged to prove the facts that gave rise to, continue, or terminate this right

For example:

• In a debt collection lawsuit: The creditor must prove the contract that gave rise to the debt, that it was not performed, and the amount owed.

• In a compensation lawsuit: The plaintiff, the injured party, must prove the unlawful act, the damages incurred, and the causal link.

• In a claim of ownership: The plaintiff, who asserts a superior right over the property, must prove the facts that give rise to their ownership or real right.

The burden of proof fact-based; each case is assessed separately.

3.2. Cases Where the Burden of Proof Shifts in the Law

The "proving allegations" rule doesn't always apply. In some cases:

• legal presumptions ,

• strict liability or dangerous liability regulations,

• the employer's liability in workplace accidents, the physician's liability, and the carrier's liability ,

The burden of proof may effectively or directly to the other party .

For example:

• In some tort cases, the injured party only the damage and the causal link ; fault is presumed, and the burden of proof of innocence rests with the perpetrator.

• In workplace accident cases, the Supreme Court's practice presumes that the employer has failed to take occupational health and safety measures; the employer obligated to prove that .

Such regulations demonstrate that burden of proof rules are applied flexibly for the purposes of equity and social policy

3.3. Limitations on Changing the Burden of Proof by Contract

As a rule, the parties have the option of shifting the burden of proof through a contract . However:

• Contrary to mandatory provisions that completely protect the weaker party ,

• In consumer transactions, unfair terms that are detrimental to the consumer,

• Undermining the protective structure of labor law against workers,

The terms and conditions may be deemed invalid.

For example, a burdensome and unfair clause in a consumer contract stating that "the burden of proof for any defects in the product rests with the consumer" would be considered invalid under consumer law . This is because the aim of consumer law is to protect the weaker party .

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4. Standards of Proof: Complete Proof, Approximate Proof, and “Most Likely”

4.1. The Meaning of Standards of Proof

The standard of proof refers to the level of conviction a judge must have . In criminal proceedings, this level is very high; "a definitive conviction beyond all reasonable doubt" is required. In contrast, the standard of proof is lower in civil proceedings because:

• The parties are private law subjects in a "free and equal" position

• Disputes do not affect public peace as severely as criminal proceedings do

• It is often impossible for a judge to arrive at the absolute truth; the aim is based on a reasonable balance of probabilities .

This is where exact proof, approximate proof , and especially the "most likely probability" come to the forefront.

4.2. Complete Proof

Complete proof is when the judge forms a strong and consistent conviction in their inner mind that a particular fact has occurred . This conviction is:

• It does not require mathematical precision

• There is no need to be "100% sure"

• However, it shouldn't be merely a possibility; that is more likely to have already happened.

In many of its rulings, the Court of Cassation states that the required level of proof in civil litigation is "prevailing probability" ; this is essentially considered an adaptation of the full standard of proof to civil litigation

4.3. Approximate Proof

In some cases, the law allows for approximate proof to suffice. Specifically:

• Interim injunction,

• Lien,

• In some temporary protection measures,

The judge may be satisfied with presumptive proof or proof of "strong probability exceeding reasonable doubt," without waiting for complete proof . Approximate proof:

• Not for the purpose of establishing a final judgment,

• It applies to temporary and protective decisions.

Here, too, the concept of "prevailing probability" comes into play; however, this time, it is more important in assessing the need for temporary protection than in determining the ultimate truth

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5. What is the "Most Likely" Criterion?

5.1. Theoretical Definition

The "most likely outcome" can be briefly defined as follows:

that an event has occurred higher, stronger, or more dominant .

In other words:

• Two possibilities are compared (happened – didn't happen),

• If the judge, after evaluating the evidence, concludes that "the probability of it having happened is greater than the probability of it not having happened,"

• The burden of proof is deemed to have been fulfilled in favor of the person asserting the fact.

The important point here is that the judge is not seeking absolute mathematical certainty , but also not settling for mere "doubt or weak probability." "Predominant probability" can be summarized as "it appears more likely to have happened."

5.2. The Difference Between Pure Probability and Overriding Probability

• Simple probability: "It may have happened, or it may not have; the evidence is balanced."

• The prevailing probability: "It is more likely that it happened; the evidence strongly points to it having happened."

If the evidence completely equal or inconclusive , meaning it doesn't strengthen one party's claim over the other, then the concept of "prevailing probability" cannot be applied. In this case, the burden of proof rule comes into play; the party bearing the burden of proof is deemed to have failed to prove their claim, and a decision is made against them.

5.3. Relationship with Burden of Proof

The "prevailing probability" is directly related to the distribution of the burden of proof:

• First, it is determined which fact will be proven by which party

• Then the evidence presented by that side is evaluated together with the counter-evidence

• If there is a strong probability that the events in question occurred , the burden of proof is considered fulfilled.

Therefore, the "most likely possibility" is:

• a standard of proof (the level of persuasion required for a legal fact to be accepted).

• also a target for the party bearing the burden of proof .

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6. The “Most Likely Possible” in Turkish Practice

6.1. The Approach of the Supreme Court

In its long-standing jurisprudence, the Court of Cassation has summarized the standard of proof in civil litigation in various decisions as follows:

• In civil litigation, it is not necessary to "definitely and completely establish the truth" for proof .

• It is sufficient for the judge to form a strong conviction, based on the evidence, that the event occurred as alleged .

• In cases of doubt and equal evidence, the rules regarding the burden of proof apply.

This approach demonstrates that in civil litigation, the pursuit of truth is achieved at the probability level ; it shows that the "preponderance of evidence" standard is adopted, either explicitly or implicitly

6.2. Typical Areas of Dispute

The "overcoming probability" criterion is frequently raised, particularly in the following types of disputes:

1. Compensation Claims Arising from Traffic Accidents

   • Whose fault is it?

   • The type of impact,

   • Factors such as speed, road conditions, lighting, and seatbelt use
     are considered together with expert reports, diagrams, witness testimonies, and traffic accident reports the most likely cause .

2. Work Accident and Occupational Disease Cases

   • Whether the accident occurred during work or outside the workplace,

   • Whether the employer has taken the necessary occupational safety measures,

   • Whether the worker is at fault is determined by evaluating the evidence as a whole. In workplace accidents, the presumption of fault and the employer's aggravated liability are applied together, with the likelihood of fault being considered
     

3. Medical Malpractice (Physician Liability) Lawsuits

   • Whether the medical intervention was performed in accordance with the requirements of medical science,

   • Distinguishing between complications and malpractice,

   • Whether informed consent was given is assessed through expert reports from medical professionals, patient files, and witness statements. A balance is found between the presumption of complication in favor of the physician and the easing of the burden of proof in favor of the patient , within the framework of the prevailing probability standard.
     

4. Consumer Disputes

   • The existence of defective goods or services,

   • Whether the shame is hidden or open,

   • Issues such as delivery date and notification period
     are evaluated using invoices, message records, service forms, and witness testimonies; the principle of protective interpretation in favor of the consumer and the most likely scenario are applied together.

5. Rent and Eviction Cases

   • Whether the eviction undertaking was obtained through vitiated consent,

   • Whether the tenant has made the payment or not,

   • The veracity of reasons cited for eviction, such as necessity or reconstruction/reconstruction,
     is assessed based on the most likely evidence, considering official documents, bank records, witness statements, and expert analysis.

These examples demonstrate that the “prevailing probability” is not an abstract theory, but a criterion concretized in everyday judicial practice

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7. The Relationship Between Types of Evidence and the “Most Likely” Probability

7.1. Expert Reports

In matters requiring technical or specialized knowledge, expert reports play a crucial role in shaping a judge's opinion. An expert report:

• is consistent, scientific, and explanatory ,

• If it is consistent with the other evidence in the file ,

• the party reasonable explanations ,

It becomes evidence that strengthens the "prevailing probability" in the eyes of the judge

However:

• If there are contradictions in the report,

• If it is inconsistent with the factual evidence in the file,

• If it is based on assumptions,

The judge is not obligated to rely on this report; if necessary, a supplementary report or a new expert . For the lawyer, the strategy concrete and scientific objections that will tip the expert report in favor of the "most likely outcome .

7.2. Witness Statements

Witness statements, in particular:

• In family law disputes,

• Employment relationship, the fact of actual work, mobbing allegations,

• In cases involving situations that are difficult to fully prove with written documents, such as oral agreements, actual use, or actual delivery,

It is of vital importance.

The judge is evaluating the witness statements:

• The witness's ability to see and perceive the event,

• The consistency of the statement ,

• Closeness and mutual interest with the parties ,

• The consistency of the statement with other evidence in the file ,

It takes this into consideration. The consistency of witness statements with each other and with other evidence strengthens the "most likely scenario." Otherwise, contradictory testimonies from witnesses can lead to an imbalance in the evidence

7.3. Presumption and the Ordinary Course of Life

In evidentiary law, presumptions and the ordinary course of eventsare among the most important tools shaping the prevailing probability. The judge:

• Human behavior,

• The necessities of economic life,

• The practical limits of the time-space relationship,

Taking certain facts into consideration, it may accept some facts presumptive evidence . For example:

• Assuming that the person receiving treatment in the hospital has received information from the doctor about their treatment process,

• It is acceptable to assume that an employee who has worked at the same workplace for a long time is familiar with certain routine procedures

• To presume the existence of a rental relationship based on someone's long-term rent payments.

If one party makes a claim that is clearly contrary to the ordinary course of life, very strong evidence . Otherwise, the more likely outcome what is ordinary .

7.4. Electronic Evidence and Digital Traces

Today:

• WhatsApp conversations,

• Email records,

• SMS messages,

• Bank transactions,

• Camera recordings,

It is frequently used as a means of proof. These pieces of evidence include:

• Its authenticity (originality, whether it has been manipulated),

• Method of obtaining evidence (legality),

• The integrity of the records (whether they are presented selectively or not),

This is examined from various perspectives. In particular, timestamps, IP records, and location datacontribute to the judge forming a "higher probability" case.

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8. Limitations and Criticisms of the "Most Likely" Criterion

8.1. Problems from the Perspective of Legal Security

The concept of "prevailing probability" is, by its very nature, abstract and open-to-interpretation criterion. This abstractness has led to some criticism:

• It is not always clear in which situation the probability is "more likely," and in which it is "equal" or "weak."

• Different judges may draw different conclusions from the same set of evidence

• This situation the predictability of judicial decisions .

However, it should be remembered that the evaluation of evidence in civil proceedings always involves a degree of discretion . What is important is that the judge:

• Explaining its decision with logical and verifiable reasoning

• The Supreme Court's review essentially focuses on the accuracy of this reasoning.

8.2. Obligation to Write Reasoned Decisions

The "prevailing probability" standard emphasizes the judge's obligation to write a reasoned decision . The judge:

• Which facts does he consider to be established?

• Which evidence do you consider superior and why?

• Why he/she doesn't find the other side's claims sufficient,

It must be clearly stated. General and clichéd phrases such as "The evidence has been evaluated together, the plaintiff's claim has not been proven" are insufficient in terms of concretizing the standard of proof.

With a sound reason:

• On what evidence was the most likely scenario determined ?

• Why is one side given precedence when the narratives of the parties contradict each other ?

• How the presumptions and the ordinary course of life are taken into consideration ,

It should be explained in detail.

8.3. Right to a Fair Trial and Standards of Evidence

The vague application of evidentiary standards can also create problems in terms of the right to a fair trial (right to be heard, equality of arms, right to a reasoned judgment). In particular:

• Interpretations that effectively increase the burden of proof against the weaker party (consumer, worker, patient, etc.),

• Restriction of opportunities to present evidence,

• The judge's one-sided evaluation of the evidence,

This could lead to violations of these rights.

Therefore, when applying the "more likely" criterion, a balance must be maintained between the parties ; the burden of proof and the standard of proof fairly .

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9. Strategic and Practical Recommendations for Lawyers

9.1. Creating an Evidence Map Before Commencing Litigation

One of the most important things a lawyer should do before starting a case an "evidence map" :

• Who has to prove which fact ?

• What evidence does the client have ?

• What evidence is obtainable, and what evidence is very difficult or impossible to obtain?

• Is the available evidence strong enough to outweigh the potential evidence presented by the opposing side, and thus secure a victory in favor of the client?

In conclusion, this analysis concludes:

• Whether a lawsuit will be filed,

• If it is to be opened, what legal grounds will be relied upon?

• Alternatively, it should be determined whether there are possible types of claims that would lighten the burden of proof or create presumptions

9.2. In Petitions, Not Only the Incident but Also the Proof Strategy Should Be Constructed

In particular, the initial statement of claim and the response statement should not only be texts describing the events; they should also form the framework of the evidence strategy .

• Whichever fact is to be proven with which evidence must be clearly stated

• Situations where the burden of proof lies with the other party must be presented with legal justification

• The circumstances and the ordinary course of life should be stated clearly,

• The Supreme Court's emphasis on the "most likely scenario" should be reiterated with appropriate wording.

Thus, the judge is guided from the outset to view the dispute within the framework of rules and standards of evidence .

9.3. Shaping Expert and Witness Evidence in Favor of the "Most Likely"

The lawyer should not merely "present" expert and witness evidence; fully synchronize it .

• When preparing the witness list, consideration should be given to the witnesses' ability to see the event, their impartiality, and which aspects of the event they will shed light on.

• In expert examinations, questions should be formulated in a way that is as concrete and non-leading as possible , but clarifies the facts

• Objections to the report should be framed not solely around the results, but the methodology, data set, and assumptions .

The aim is to create the impression before the judge that,
"When the evidence in this case is considered as a whole, the client's scenario most likely true."

9.4. Building Arguments Based on Presumption and the Ordinary Course of Life

Many cases may lack written evidence or direct witnesses. In these situations, the lawyer:

• From the rules of material life,

• From economic and social realities,

• From the psychological and sociological characteristics of human behavior

By using this, one can develop an argument in favor of the "more likely possibility".

For example:

• A person's consistent payment of rent over many years without objection constitutes strong evidence in favor of the existence of a rental relationship

• An employee's consistent employment at the same workplace for a long period of time supports claims of an actual employment relationship and entitlement to wages.

Such arguments, especially in the absence of written evidence, a plausible and dominant scenario in the judge's mind regarding how the event occurred .

9.5. Discussing the Reasoned Judgment in terms of Proof Standards in Appeal/Cassation

In the appeal or cassation process, it is not sufficient for the lawyer to simply say "there was an error in the assessment of evidence." The following questions should be asked:

• Has the court clearly explained in its reasoning which evidence it considered superior and why ?

• Are there any illogical or improbable interpretations among the evidence?

• Has the court correctly determined which side bears the burden of proof ?

• Was the "most likely outcome" assessment based on concrete reasons or on clichés?

In this context, in appeal/cassation petitions:

• both from a procedural law perspective,

• And also errors in evaluating evidence on the merits,

It should be presented systematically.

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10. Conclusion

In Turkish civil procedural law, one of the most critical factors determining the outcome of a case is the burden of proof and the standards of proof. The legislator with Article 6 of the Turkish Civil Code and the provisions on proof in the Code of ; the precedents of the Supreme Court have concretized this framework "prevailing probability" standard.

As seen in this article:

• The burden of proof is a risk distribution tool that determines who loses if a fact cannot be proven

• In civil proceedings, the standard of proof is not "absolute conviction beyond all reasonable doubt" as in criminal proceedings, but "overriding probability .

• While freely assessing the evidence, the judge considers expert reports, witness statements, electronic records, presumptive evidence, and the ordinary course of events; in this process, a convincing and consistent set of evidence determines the "most likely probability."

• The reasoned judgment must explain which evidence was considered superior and on what grounds, and how the more likely probability was determined.

• For lawyers, proof is not merely presenting evidence; a process of strategic planning, argumentation, and evidence management. Creating an evidence roadmap before the trial begins, formulating a proof strategy in the petitions, coordinating expert and witness evidence, and building arguments based on presumptions and the ordinary course of events are fundamental tools for creating a stronger probability in favor of the client.

In conclusion, "burden of proof and standards of proof" often translates into "winning or losing a case" in practice. A lawyer who consciously and systematically uses the "overriding probability" criterion will be able to protect their client's rights much more effectively, both in the first instance proceedings and in the appeal/cassation stages.